The proposed conference will be the first Gordon Conference on Three-dimensional Electron Microscopy of Macromolecules. Electron microscopy has developed extremely rapidly over the last few years as a tool for structure research at the molecular level. Important technical breakthroughs have recently been made which enable three-dimensional structure to be determined more accurately than before, and which open the way to a study of structure essentially under controlled physiological conditions. As a result there are now exciting new opportunities for understanding biological mechanisms and principles of molecular design. The focus of this meeting will be on the novel electron microscopic methods being developed for preserving structure in the native hydrated state, for imaging molecules in frozen solution, for reducing radiation damage by low dose and low temperature and for extracting high resolution three-dimensional information from images of molecules in isolation, in complex assemblies and in crystalline arrays. Important recent structural findings, relating especially to membrane and contractile proteins, will also be emphasized. This conference will help catalyze the further development of this field by bringing together many of the key investigators and allowing them to discuss their latest and perhaps even incomplete studies in a unique and informal setting. Speakers are being chosen on the basis of the importance of their recent research contributions and the potential of their particular approach in future structure research. Topics to be covered include: electron microscopy of specimens preserved in frozen solution, high resolution structure determination from two-dimensional crystals, combined electron microscopy and X-ray diffraction, correlation averaging of isolated molecules, crystallization methods, related approaches in structural cell biology, and recent structural findings dealing with membrane proteins, filamentous proteins and other complex molecular assemblies.